The Experts below are selected from a list of 45 Experts worldwide ranked by ideXlab platform
Hwanmyeong Yeo - One of the best experts on this subject based on the ideXlab platform.
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development of pitch pine glued laminated timber for structural use improvement of bending capacity of pitch pine glulam by using domestic larch laminars
Journal of the Korean wood science and technology, 2007Co-Authors: Kwang Mo Kim, Joo Saeng Park, Kugbo Shim, Wunsub Kim, Jinah Lim, Hwanmyeong YeoAbstract:This study was carried out to scrutinize possibility of manufacturing pitch pine (Pinus rigida) glued laminated timber in order to add values of pitch pine trees. Also, it was investigated to improve bending performance of pitch pine glulam. Pitch pine was imported as one of major plantation species in Korean peninsula. Machine Stress rated grades of pitch pine lumber mostly ranged between E7 and E9. which grades were more or less inferior to producing high quality glulam. However, the adhesive properties between pitch pine and pitch pine, and between pitch pine and Japanese larch (Larix kaempferi Carr.), such as shear bond strength, wood failure rate and de-lamination rate of bonded layer submerged in cold and boiling water, were higher than Korean Standard criteria. These properties are essential for manufacturing glulam with single species or multiple species. The modulus of rupture (MOR) of pitch pine glulam exceeded the criterion of Korean Standard for glulam strength grade but modulus of elasticity (MOE) was lower than the criterion. On the other hand, the bending performances (MOR and MOE) were improved 20 percent by mixing with Japanese larch laminar. It is effective to arrange higher quality Japanese larch laminar at the outer layer of glulam for improving bending performances. In conclusion, it is possible to use low quality pitch pine as laminar of structural glulam for adding values of pitch pine.
J Ilic - One of the best experts on this subject based on the ideXlab platform.
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acoustic segregation of pinus radiata logs according to stiffness
Annals of Forest Science, 2002Co-Authors: Colin A Matheson, Ross L Dickson, David J Spencer, Bill Joe, J IlicAbstract:Wood stiffness varies enormously both within and between trees, so it is inevitable that low-grade solid wood products are produced from some trees. Accordingly, it would be highly desirable to segregate logs to ensure that only those logs with predominantly high stiffness wood are processed into structural lumber products. This study examined whether sound flight velocity (m s -1 ) could be used as a direct measure of wood stiffness to allow such segregation. Trees of radiata pine were measured before and after harvest with a non-destructive acoustic device (Stress wave timer) to see if there was a relationship between sound wave velocity in either standing trees or logs and Machine Stress-grades of boards derived from those trees and logs. The speed of sound along logs was sufficiently closely correlated with wood stiffness to allow logs to be sorted into classes. A highly significant and positive relationship was found for acoustic measurements made in logs and a weaker, but still si- gnificant, relationship existed for acoustic measurements made in standing trees. Such segregation of logs according to wave velocity measured in the field may save a large sawmill between A$1-4m each year. Acoustic methods may also be used as an indirect tool for selection provided the heritability of the measurements is high enough and there is significant genetic correlation with genetic values for wood stiffness. From ano- ther experiment we have estimated the heritability of several acoustic measures and hope to be able to estimate genetic relationships with wood quality soon. modulus of elasticity / wood, acoustics / sound speed / selection
Kwang Mo Kim - One of the best experts on this subject based on the ideXlab platform.
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development of pitch pine glued laminated timber for structural use improvement of bending capacity of pitch pine glulam by using domestic larch laminars
Journal of the Korean wood science and technology, 2007Co-Authors: Kwang Mo Kim, Joo Saeng Park, Kugbo Shim, Wunsub Kim, Jinah Lim, Hwanmyeong YeoAbstract:This study was carried out to scrutinize possibility of manufacturing pitch pine (Pinus rigida) glued laminated timber in order to add values of pitch pine trees. Also, it was investigated to improve bending performance of pitch pine glulam. Pitch pine was imported as one of major plantation species in Korean peninsula. Machine Stress rated grades of pitch pine lumber mostly ranged between E7 and E9. which grades were more or less inferior to producing high quality glulam. However, the adhesive properties between pitch pine and pitch pine, and between pitch pine and Japanese larch (Larix kaempferi Carr.), such as shear bond strength, wood failure rate and de-lamination rate of bonded layer submerged in cold and boiling water, were higher than Korean Standard criteria. These properties are essential for manufacturing glulam with single species or multiple species. The modulus of rupture (MOR) of pitch pine glulam exceeded the criterion of Korean Standard for glulam strength grade but modulus of elasticity (MOE) was lower than the criterion. On the other hand, the bending performances (MOR and MOE) were improved 20 percent by mixing with Japanese larch laminar. It is effective to arrange higher quality Japanese larch laminar at the outer layer of glulam for improving bending performances. In conclusion, it is possible to use low quality pitch pine as laminar of structural glulam for adding values of pitch pine.
Tord Isaksson - One of the best experts on this subject based on the ideXlab platform.
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modelling the variability of bending strength in structural timber length and load configuration effects
Report TVBK; 1015 (1999), 1999Co-Authors: Tord IsakssonAbstract:The load carrying capacity of a beam of structural timber is dependent both on the span of the beam and the type of loading. The longer the beam and the more uniform the moment distribution, the lower the load carrying capacity. This phenomenon is due to the variability of material properties within a piece of timber. This variability is, in turn, due to the presence of knots, the slope of grain and other abnormalities in the timber. The Swedish building code does not take into account the dependence on length and load, while the Eurocode includes the effect of length. The scope of this study was to investigate the variability of bending strength within and between members of structural timber and to find a way of modelling this variability. Using the model, the effect of length and type of loading on the load carrying capacity of a beam has been investigated. The experimental tests were performed on Norway Spruce (Picea Abies). The first part of this thesis presents a description of timber as a structural material, the Weibull theory on length and load configuration effects and reliability- based analysis of the length and load configuration effects. The next part deals with the experimental investigation, preceded by a section on the non-destructive grading of timber, including both visual and Machine Stress grading. The grading parameters are essential tools when deciding how and where to test the timber. In total, 673 sections distributed over 132 beams were tested successfully in several weak sections within a beam. The tests were performed using a newly developed test set-up. Comparative tests were performed using the test arrangement prescribed in the European code. No significant differences between the results from the different set-ups were found. Furthermore, the grading parameters were compared with the actual strength. A non-parametric study of the length and load configuration effect using only the test data gave a shape factor of 0.1 in the Weibull distribution. The length and load configuration effects were, in general, quite small. The simulation of tests of bending strength according to the European, North American and Australian codes gave small differences, although the codes differ as to where on a timber the test should be performed. A model of the variation of bending strength within and between timber members was developed. The model is based on stochastic variables such as the distance between weak sections, length of weak sections, strength of weak sections and strength between weak sections. Several alternative inputs were investigated. The thesis is concluded with the presentation of a study on length and load configuration effects using the statistical model of the variation in bending strength. The effect was studied using direct comparison of strengths (Weibull theory), reliability-based methods (level II) and a calibration using the Swedish code format. The results from the latter could be introduced in a code. Compared with today's design, the strength of a beam could be increased by 10 % (depending on the length and type of loading).
Colin A Matheson - One of the best experts on this subject based on the ideXlab platform.
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acoustic segregation of pinus radiata logs according to stiffness
Annals of Forest Science, 2002Co-Authors: Colin A Matheson, Ross L Dickson, David J Spencer, Bill Joe, J IlicAbstract:Wood stiffness varies enormously both within and between trees, so it is inevitable that low-grade solid wood products are produced from some trees. Accordingly, it would be highly desirable to segregate logs to ensure that only those logs with predominantly high stiffness wood are processed into structural lumber products. This study examined whether sound flight velocity (m s -1 ) could be used as a direct measure of wood stiffness to allow such segregation. Trees of radiata pine were measured before and after harvest with a non-destructive acoustic device (Stress wave timer) to see if there was a relationship between sound wave velocity in either standing trees or logs and Machine Stress-grades of boards derived from those trees and logs. The speed of sound along logs was sufficiently closely correlated with wood stiffness to allow logs to be sorted into classes. A highly significant and positive relationship was found for acoustic measurements made in logs and a weaker, but still si- gnificant, relationship existed for acoustic measurements made in standing trees. Such segregation of logs according to wave velocity measured in the field may save a large sawmill between A$1-4m each year. Acoustic methods may also be used as an indirect tool for selection provided the heritability of the measurements is high enough and there is significant genetic correlation with genetic values for wood stiffness. From ano- ther experiment we have estimated the heritability of several acoustic measures and hope to be able to estimate genetic relationships with wood quality soon. modulus of elasticity / wood, acoustics / sound speed / selection
